Circulating tumor cells in prostate cancer diagnosis and monitoring: an appraisal of clinical potential

Abstract

Circulating tumor cells (CTCs) have emerged as a viable solution to the lack of tumor tissue availability for patients with a variety of solid tumors, including prostate cancer. Different approaches have been used to capture this tumor cell population and several of these techniques have been used to assess the potential role of CTCs as a biological marker to predict treatment efficacy and clinical outcome. CTCs are now considered a strong tool to understand the molecular characteristics of prostate cancer, and to be used and analyzed as a 'liquid biopsy' in the attempt to grasp the biological portrait of the disease in the individual patient.

Fig. 1

a Picture of the GEDI microfluidic device. b 10× magnification immunofluorescence mosaic image reconstruction of the GEDI chip where the geometric distribution of the microposts is clearly discernable; bar 2,000 µm. c 63× magnification images of CTCs isolated from a representative CRPC patient, before (a–f) and after (g– l) taxane treatment. Blue DAPI (a, g); red cytokeratin (b, h); yellow CD-45 (c, i); green AR (d, j); purple tubulin (e, k); merge (f, l). CTCs were defined as CK⁺/CD-45^–/DAPI⁺ cells. Before treatment, AR localization is mainly nuclear, as expected (d, f), and tubulin presents with a diffuse pattern, representative of the typical intricate micro-tubule network (e). After taxane treatment, AR is sequestered into the cytoplasm (j, larrowhead) consequent to drug activity, as shown by the presence of microtubule bundling (karrow). Dashed line micropost edge. Bars 5 µm. Images courtesy of Matt Sung, Ph.D. AR androgen receptor, CRPC castration-resistant prostate cancer, CTC circulating tumor cells, GEDI geometrically enhanced differential immunocapture